cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

Showing 1-4 of 4 results.

A163353 G.f.: A(x,y) = Sum_{n>=0,m>=0} (2^m-1)^n*x^n * log(1+y)^m/m!.

Original entry on oeis.org

1, 1, 0, 1, 1, 0, 1, 4, 4, 1, 0, 1, 13, 44, 67, 56, 28, 8, 1, 0, 1, 40, 360, 1546, 4144, 7896, 11408, 12866, 11440, 8008, 4368, 1820, 560, 120, 16, 1, 0, 1, 121, 2680, 27550, 180096, 866432, 3308736, 10453960, 27991600, 64472200, 129002640, 225783740, 347370800, 471435000, 565722640, 601080385, 565722720, 471435600, 347373600
Offset: 0

Views

Author

Paul D. Hanna, Jul 25 2009

Keywords

Comments

From Manfred Boergens, Apr 07 2025: (Start)
T(n,k) is the number of collections of k [n]-subsets with union=[n]; with [0] = {}.
For n > 0: If more than half of the subsets are drawn their union covers [n] (see Formula). - The proof is based on 2^(n-1) being the number of subsets of [n] with one fixed element of [n] missing.
For collections of nonempty subsets see A055154.
For disjoint collections of subsets see A256894.
For disjoint collections of nonempty subsets see A008277. (End)

Examples

			Triangle begins:
  1,1;
  0,1,1;
  0,1,4,4,1;
  0,1,13,44,67,56,28,8,1;
  0,1,40,360,1546,4144,7896,11408,12866,11440,8008,4368,1820,560,120,16,1;
  ...
		

Crossrefs

Cf. A000371 (row sums), A381683 (partial row sums), A134174 (main diagonal).

Programs

  • Mathematica
    Table[Sum[(-1)^(n - j)*Binomial[n, j]*Binomial[2^j, k], {j, 0,
       n}], {n, 0, 5}, {k, 0, 2^n}]//Flatten (* G. C. Greubel, Dec 19 2016 *)
  • PARI
    T(n,k)=sum(j=0,n,(-1)^(n-j)*binomial(n,j)*binomial(2^j,k))

Formula

T(n,k) = Sum_{j=0..n} (-1)^(n-j)*C(n,j)*C(2^j,k), k=0..2^n.
Row sums form A000371 (nondegenerate Boolean functions of n variables).
Main diagonal equals A134174 and is defined by the g.f.:
Sum_{n>=0} log(1 + (2^n-1)*x)^n/n!.
From Manfred Boergens, Apr 11 2024: (Start)
T(n,k) = A055154(n,k) + A055154(n,k-1) for n > 0, k > 0; A055154(n,j) are not defined for j = 0 and j = 2^n and are set = 0.
T(n,k) = C(2^n,k) for k > 2^(n-1).
T(n,k) < C(2^n,k) for k <= 2^(n-1), n > 0.
(Note: C(2^n,k) is the number of all k-subsets of P([n]).) (End)

A133990 a(n) = Sum_{k=0..n} (-1)^(n-k) * binomial(n,k) * binomial(2^k + n - 1,n).

Original entry on oeis.org

1, 1, 5, 71, 2747, 306861, 106709627, 123122238887, 492425723170553, 7012142056418141897, 361269845371107759765065, 68033187103968192731087467135, 47171609221094330538117045468744655
Offset: 0

Views

Author

Paul D. Hanna and Vladeta Jovovic, Jan 21 2008

Keywords

Examples

			G.f.: A(x) = 1 + x + 5*x^2 + 71*x^3 + 2747*x^4 + 306861*x^5 +...
where
A(x) = 1 - log(1-x) + log(1-3*x)^2/2! - log(1-7*x)^3/3! + log(1-15*x)^4/4! - log(1-31*x)^5/5! + log(1-63*x)^6/6! - log(1-127*x)^7/7! + log(1-255*x)^8/8! +...
		

Crossrefs

Cf. A134174.

Programs

  • Maple
    A133990 := proc(n) add((-1)^(n-k)*binomial(n,k)*binomial(2^k+n-1,n),k=0..n) ; end: seq(A133990(n),n=0..15) ; # R. J. Mathar, Jan 30 2008
  • Mathematica
    Table[Sum[(-1)^(n-k) Binomial[n,k]Binomial[2^k+n-1,n],{k,0,n}], {n,0,15}] (* Harvey P. Dale, Nov 24 2011 *)
  • PARI
    {a(n)=local(A=1,X=x+x*O(x^n)); A=sum(k=0,n,log(1/(1-(2^k-1)*X))^k/k!); polcoeff(A,n)}
    for(n=0,20,print1(a(n),", "))
    
  • PARI
    {Stirling1(n, k)=n!*polcoeff(binomial(x, n), k)}
    {a(n)=1/n!*sum(k=0,n,(-1)^(n-k)*Stirling1(n,k)*(2^k-1)^n)}
    for(n=0, 20, print1(a(n), ", "))

Formula

G.f.: Sum_{n>=0} (-log(1 - (2^n-1)*x))^n / n!.
a(n) = (1/n!) * Sum_{k=0..n} (-1)^(n-k) * Stirling1(n,k) * (2^k-1)^n.
From Vaclav Kotesovec, Jul 02 2016: (Start)
a(n) ~ binomial(2^n,n).
a(n) ~ 2^(n^2) / n!.
a(n) ~ 2^(n^2 - 1/2) * exp(n) / (sqrt(Pi) * n^(n+1/2)).
(End)

Extensions

More terms from R. J. Mathar, Jan 30 2008

A133991 a(n) = Sum_{k=0..n} binomial(n,k) * binomial(2^k+n-1,n).

Original entry on oeis.org

1, 3, 17, 193, 5427, 463023, 134675759, 139917028089, 527871326293913, 7281357469833220843, 368715613115281663650597, 68787958348542935934247206953, 47453320297069210448891035137347047
Offset: 0

Views

Author

Paul D. Hanna and Vladeta Jovovic, Jan 21 2008

Keywords

Crossrefs

Programs

  • Mathematica
    Table[Sum[(-1)^(n-k) * StirlingS1[n, k]*(2^k + 1)^n, {k, 0, n}]/n!, {n, 0, 12}] (* Vaclav Kotesovec, Jun 08 2019 *)
  • PARI
    a(n) = sum(k=0, n, binomial(n, k)*binomial(2^k+n-1, n)); \\ Seiichi Manyama, Feb 24 2023

Formula

a(n) = (1/n!)*Sum_{k=0..n} (-1)^(n-k)*Stirling1(n,k)*(2^k+1)^n.
G.f.: Sum_{n>=0} (-log(1 - (2^n+1)*x))^n/n!.
a(n) ~ 2^(n^2) / n!. - Vaclav Kotesovec, Jun 08 2019

Extensions

More terms from Alexis Olson (AlexisOlson(AT)gmail.com), Nov 14 2008

A136648 Inverse binomial transform of A014070: a(n) = Sum_{k=0..n} (-1)^(n-k)*C(n,k)*C(2^k,k).

Original entry on oeis.org

1, 1, 3, 43, 1625, 192785, 73792371, 94005141667, 408909577044065, 6204433373664395569, 334203804752658372354515, 64828498485572980097719939179, 45811084061472137471487315433296153, 119028111984311982345314987179033877373025, 1145664208319965667452046935744516601565935434531
Offset: 0

Views

Author

Paul D. Hanna and Vladeta Jovovic, Jan 21 2008

Keywords

Crossrefs

Cf. A014070 (C(2^n, n)), A134174.

Programs

  • Mathematica
    Table[Sum[(-1)^(n-k)*Binomial[n,k]*Binomial[2^k,k], {k, 0, n}], {n, 0, 15}] (* Vaclav Kotesovec, Jul 02 2016 *)
  • PARI
    {a(n)=sum(k=0,n,(-1)^(n-k)*binomial(n,k)*binomial(2^k,k))}
    
  • PARI
    /* Using the g.f.: */ {a(n)=my(X=x+x*O(x^n));polcoeff(sum(k=0,n,(log(1+(2^k+1)*X)-log(1+X))^k/k!)/(1+X),n)}

Formula

G.f.: A(x) = (1/(1+x))*Sum_{n>=0} [log(1 + (2^n+1)*x) - log(1+x)]^n / n!.
a(n) ~ 2^(n^2) / n!. - Vaclav Kotesovec, Jul 02 2016

Extensions

Edited by Charles R Greathouse IV, Oct 28 2009
Terms a(13) and beyond from Andrew Howroyd, Feb 02 2020
Showing 1-4 of 4 results.